Multilayer Si<inf>3</inf>N<inf>4</inf> consisting of Si<inf>3</inf>N<inf>4</inf> nanolayers with the total thickness 60 nm was deposited layer-by-layer in a low-pressure chemical vapor... more
Multilayer Si<inf>3</inf>N<inf>4</inf> consisting of Si<inf>3</inf>N<inf>4</inf> nanolayers with the total thickness 60 nm was deposited layer-by-layer in a low-pressure chemical vapor deposition process. Compared with the single-layer Si<inf>3</inf>N<inf>4</inf>, the multilayer Si<inf>3</inf>N<inf>4</inf> had one-third less oxygen concentration at the interfaces. This decreased density of electrically active centers of oxygen traps and improved quality of nanocapacitors with multilayer Si<inf>3</inf>N<inf>4</inf> dielectric.
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One-dimensional chain of core-shell pairs connected by ideal springs enables design of the metamaterial demonstrating the negative effective density and negative specific thermal capacity. We assume that the molar thermal capacity of the... more
One-dimensional chain of core-shell pairs connected by ideal springs enables design of the metamaterial demonstrating the negative effective density and negative specific thermal capacity. We assume that the molar thermal capacity of the reported metamaterial is governed by the Dulong-Petit law in its high temperature limit. The specific thermal capacity depends of the density of the metamaterial; thus, it is expected to be negative, when the effective density of the chain is negative. The range of the frequencies enabling the effect of the negative thermal capacity is established. Dependence of the effective thermal capacity on the exciting frequency for various core/shell mass ratios is elucidated. The effective thermal capacity becomes negative in the vicinity of the local resonance frequency ω0 in the situation when the frequency ω approaches ω0 from above. The effect of the negative effective thermal capacity is expected in metals in the vicinity of the plasma frequency.
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Water forms ordered hexagonally symmetric structures (snow crystals) in its solid state, however not as liquid. Typically, mists and clouds are composed of randomly moving small droplets lacking any ordered structure. Self-organized... more
Water forms ordered hexagonally symmetric structures (snow crystals) in its solid state, however not as liquid. Typically, mists and clouds are composed of randomly moving small droplets lacking any ordered structure. Self-organized hexagonally patterned microdroplet clusters over locally heated water surfaces have been recently observed. However, many aspects of the phenomenon are far from being well understood including what determines droplets size, arrangement, and the distance between them. Here we show that the Voronoi entropy of the cluster tends to decrease indicating to their self-organization, while coupling of thermal effects and mechanical forces controls the stability of the clusters. We explain the balance of the long-range attraction and repulsion forces which stabilizes the cluster patterns and established the range of parameters, for which the clusters are stable. The cluster is a dissipative structure similar to self-organized Rayleigh-Bénard convective cells. Micr...
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Low-density polyethylene, polypropylene, and polycarbonate were exposed to cold air plasma treatment. The decay of electret response, hydrophobic recovery, and mechanical relaxation of polymers were studied experimentally. The... more
Low-density polyethylene, polypropylene, and polycarbonate were exposed to cold air plasma treatment. The decay of electret response, hydrophobic recovery, and mechanical relaxation of polymers were studied experimentally. The three-exponential decay kinetic model was used for the treatment of mechanical and electret responses. The characteristic time scales of mechanical and electret responses turned out to be very close. The “longest” relaxation time, extracted from the experimental study of the hydrophobic recovery, was also close to the corresponding characteristic time spans of electret and mechanical responses. The kinetics of surface processes taking place in polymers is controlled by the mobility of their functional groups, represented by the bulk relaxation spectra. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 198–205
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Abstract Cold plasma treatment leads to the electrical charging of liquid organic (polydimethylsiloxane) surfaces. Water droplets placed on the surface of cold radiofrequency plasma treated polydimethylsiloxane oil were used as probes... more
Abstract Cold plasma treatment leads to the electrical charging of liquid organic (polydimethylsiloxane) surfaces. Water droplets placed on the surface of cold radiofrequency plasma treated polydimethylsiloxane oil were used as probes enabling the estimation of the specific surface charge supplied by plasma to polydimethylsiloxane. The specific surface charge was also established independently by the electrostatic pendulum. The surface charge density was estimated as σ ≅ 0.5 ÷ 3 μC/m 2 .
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Physical mechanisms of the interaction of cold plasmas with organic surfaces are discussed. Trapping of plasma ions by the CH2 groups of polymer surfaces resulting in their electrical charging is treated. Polyethylene surfaces were... more
Physical mechanisms of the interaction of cold plasmas with organic surfaces are discussed. Trapping of plasma ions by the CH2 groups of polymer surfaces resulting in their electrical charging is treated. Polyethylene surfaces were exposed to the cold radiofrequency air plasma for different intervals of time. The change in the wettability of these surfaces was registered. The experimentally established characteristic time scales of the interaction of cold plasma with polymer surfaces are inversely proportional to the concentration of ions. The phenomenological kinetic model of the electrical charging of polymer surfaces by plasmas is introduced and analyzed.
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ABSTRACT
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Electrowetting of silicone oil lubricated PC + EC substrates. (A)U= 0 V; (B)U= 55 V.
Research Interests: Materials Science, Polymer, RSC, Dissipation, Voltage, and 3 moreElectrowetting, Honeycomb, and Polycarbonate
The presented work demonstrates that powerful laser radiation causes changes in absorbance spectra of epoxy resin and polyethylene. Thin polymer films were located between infrared AgBrCl optical fibers and exposed to the radiation of CO2... more
The presented work demonstrates that powerful laser radiation causes changes in absorbance spectra of epoxy resin and polyethylene. Thin polymer films were located between infrared AgBrCl optical fibers and exposed to the radiation of CO2 laser. The outpot of the laser source has been varied in the range 0-8.5 Wt. Absorbance spectra were measured by FTIR spectrophotometer. It was revealed that characteristic absorbance peaks of polymers decay under the powerful IR light. The apparent dependence of peak magnitude on IR radiation power has been established. The mathematical theory of the observed effect was worked out. Authors suggested that the effect under discussion is caused by oxygen-free thermal action of IR radiation on the chemical structure of polymer materials. The revealed effect could be effectively used for the lowering of losses in adhesive contacts of IR optic elements. The novelty of the proposed method lies in the fact that thermal treatment is localized strictly in adhesive contact, optical elements to be contacted (fibers, lenses, etc.) which are highly transparent in IR don't experience the IR radiation, but polymer adhesive is subjected to a temperature rise.
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This work presents the new approach to the investigation of mass transport process in polymers. The Fiber Optic Evanescent Wave Spectroscopy has been used for the real time investigation of diffusion processes in glassy polymers. Unclad... more
This work presents the new approach to the investigation of mass transport process in polymers. The Fiber Optic Evanescent Wave Spectroscopy has been used for the real time investigation of diffusion processes in glassy polymers. Unclad AgClBr fibers of 0.9 mm diameter were dip coated by polystyrene layers of 1 - 30 micrometers thickness. The transmission of the fibers in the mid-IR was measured using a Fourier Transform Infrared spectrometer. The penetration of liquids into these layers gave rise to significant changes in the measured spectrum. These changes were used for diffusion studies in situ. The mathematical model, which allows realizing the quantitative treatment of experimental data, was developed. The model details with processes which take place at two interfaces: polymer/liquid and polymer/optical fiber. It was established that the initial stage of diffusion is of the strictly Fickian character. The model permitted us to calculate the coefficient of diffusion of water in polystyrene with a high accuracy. The huge amount of experimental points, which could be obtained by our method, allows calculation of the equilibrium concentration of penetrating liquid with an extremely high precision. This advantage of FEWS procedure offers a high accuracy of calculations of parameters of diffusion. It must be emphasized that the thickness of the film that could be defined with the least precision doesn't affect on final results. The final stage of diffusion is non-Fickian.
Research Interests: Engineering, Materials Science, Fiber Optics, Water, Spectroscopy, and 14 moreMathematical Modeling, Sensors, Diffusion, Interfaces, Mass Transport, EVANESCENT WAVE, Real Time, Mathematical Model, Spectrum, Fiber Optic, Optical Fibers, Spectrometers, Fourier Transforms, and Fourier transform infrared
Fiber Evanescent Wave Spectroscopy (FEWS) is a very useful method for non-invasive and non-destructive biomedical diagnosis. We have developed a FEWS system that makes use of a Fourier Transform Infrared (FTIR) spectrometer and IR... more
Fiber Evanescent Wave Spectroscopy (FEWS) is a very useful method for non-invasive and non-destructive biomedical diagnosis. We have developed a FEWS system that makes use of a Fourier Transform Infrared (FTIR) spectrometer and IR transmitting AgBrCl fibers. The ...
Research Interests: Engineering, Materials Science, Optics, Spectroscopy, Proceedings, and 12 moreBiomedical Optics, Skin Cancer, Infrared spectroscopy, Skin Lesion Diagnosis, EVANESCENT WAVE, Infrared, Fourier transform infrared spectroscopy, Clinical Study, Fiber Optic, Penetration Depth, Stratum Corneum, and Fourier transform infrared
Fiberoptic Evanescent Wave Spectroscopy (FEWS) has been used for measurements of the absorption of very small (0.1mg) fragments of urinary calculi in the mid-IR. Such measurements were used for the determination of the chemical... more
Fiberoptic Evanescent Wave Spectroscopy (FEWS) has been used for measurements of the absorption of very small (0.1mg) fragments of urinary calculi in the mid-IR. Such measurements were used for the determination of the chemical composition of each fragment. When large urinary stones are fragmented, it is possible to use this method for determining the chemical composition of the inner part and the outer part of the stone. We examined 40 urinary calculi and found that in 1/3 of them the inner part and the outer parts are identical. In 2/3 the inner part is different than the outer part. This change is not revealed by standard chemical methods that provide an average chemical composition. The novel FEWS method would be useful for the analysis of urinary calculi.